Vacuum Failures Can Hurt Or What I Learned Reading ASRS
Reports

Are you prepared for a vacuum failure? If
you were asking yourself what is a vacuum failure, I would
guess you are not ready for one. Recently, in reviewing
material about new technology aircraft and their various
types of electronic display panels, I wondered how many of
today's pilots practice flying the new "glass cockpit"
aircraft using their backup instruments. This led to the
question about how many pilots of traditional aircraft
practice flying needle, ball, and airspeed.

Do we even need to practice flying with
backup instruments? Or is this one of those instrument
flying skills that is going the way of knowing how to fly a
non-directional beacon (NDB) approach in today's world of
GPS approaches and multi-panel displays? Based upon some of
the information I received from one of the leading makers of
vacuum-related equipment, this company says that, in my
words, flying with anything less than dual vacuum systems is
a hazardous operation. The fact that thousands of pilots
have flown thousands of hours for decades with only one
vacuum system would dispute this idea. So the issue then may
be one of product liability rather than operational
necessity. But, I would also bet that many of those pilots
flying single vacuum systems were like an old U.S. Air Force
colonel I once knew. When he wanted to practice instrument
flying with a safety pilot, his idea of practice was to fly
using only needle, ball, and airspeed. For him, if he ever
had a real vacuum failure and had to use his backup system
of needle, ball, and airspeed, this would not be an
emergency situation for him, but rather just another
opportunity to practice his basic instrument skills.

But whether you fly an aircraft with one or
two vacuum systems or have one of the various alternative
vacuum backup systems or have an electrically powered
artificial horizon as a backup, the question remains, are
you proficient in the use of whatever instrument backup
system you have onboard your aircraft? Can you fly your
backup system to approach minimums for your airport of
intended landing or do you give yourself a way out by
setting higher personal minimums for yourself?

I wanted to see what pilots had to say about
vacuum system failures, so I used the Internet to search
National Aeronautics and Space Administration's (NASA)
Aviation Safety Reporting System (ASRS). I was surprised at
the results my search request for "Title 14 Code of Federal
Aviation Regulations part 91 general aviation aircraft
failures in instrument metrological conditions" produced.
While I was expecting to find a few reports dealing with
vacuum pump failures, I found more reports about electrical
failures, generator failures, and more surprising, autopilot
failures resulting in altitude deviations, tracking
problems, and loss of control.

In reading the narratives describing the
reported incidents, there seemed to be two common themes
repeated throughout the many reports. First, some of the
pilots were slow in detecting the loss of navigation
equipment or control equipment, which compounded the
problem. The second group, as noted in one report, failed to
see the "big picture" of the incident. In one case, once the
aircraft situation was under control, rather than land in
visual conditions when able, the pilots continued their
flight in IMC conditions to their home airport. In the
report, it was said their continued flight was a result of
"get-homeitis" rather than based upon good decision-making.

In summarizing a few of the reports, it is
important to always fly the aircraft when something happens.
Having a backup handheld radio or GPS can keep you
communicating and navigating when your electrical system
dies. Being able to quickly detect equipment failures by
having a good instrument scan may keep you in control of
your aircraft. When flying single-pilot or at night or when
weather conditions are down to minimums, you need to have a
good divert plan and have your backup gear out and ready to
use. Finally, I think good judgment is important when
dealing with any emergency situation. Flying past a nearby
acceptable landing site in visual metrological conditions
while you are in the clouds dealing with an in-flight
emergency may not be the best example of good decision
making.